Monday, December 8, 2014

Philosophical realism is not what you think

One of the themes of this blog is to counter bad ideas of science. I am not interested in the fringe pseudosciences, but the ideas bad enuf to be taught in Harvard classrooms.

The chief offenders are the theoretical physicists pushing wacky untestable ideas, and the philosophers and historians pushing paradigm shift theory.

Philosopher and former biologist Massimo Pigliucci explains how nearly all philosophers and historians of science have adopted a view of science that is diametrically opposed to what most scientists think. He attributes the difference to a lack of self-awareness on the part of scientists.

Pigliucci's philosophy of science is the realism-antirealism debate. You might think that this would be something mildly sensible like the Bohr-Einstein debates of the 1930s, but it is not. A realist is someone who decides what is real according to the prevailing paradigm. An anti-realist is someone who relies on empirical evidence. All the modern philosophers of science are realists.

For examples, he says that Ptolemy and Newton were fundamentally wrong, because Copernicus and Einstein respectively replaced them with qualitatively different theories. Likewise classical mechanics wrong because it was replaced by quantum mechanics. Only an anti-realist would say that Newtonian gravity is correct as applied to getting Apollo 11 to the Moon.

The paradigm shifters go further, and say that Newtonian mechanics cannot even be compared to relativity because mass means something different in the two theories.

The philosophers are wrong on many levels. Mass does not mean something different, and Newtonian mechanics certainly is correct in its domain of applicability. More importantly, the philosophers are wrong about the qualitative differences.

These theories do not really contradict. Consider Ptolemy and Copernicus. It is a simple mathematical fact that Sun-centered and Earth-centered coordinate systems are mathematically equivalent. XX century physics recognizes that, and both are considered valid. Ptolemy was considered with the appearance with the sky, and does not attempt a 3D model. He does have some arguments for the Earth being stationary, but that has almost nothing to do with his model. I do not know whether he realized that his main epicycles could be interpreted as the Earth's revolution, but that is essentially what Copernicus did.

Thus Copernicus's contribution was essentially to take Ptolemy's 2D model and turn it into a 3D model by making a frame choice and an interpretation of the major epicycles. That contribution had some conceptual advantages, but it was more or less mathematically equivalent as it did not make much difference to the predictions of what we see in the sky.

This example is crucial to paradigm shift theory, because the Copernicus model had no measurable advantages over Ptolemy. This is used to support the goofy idea that scientific progress is illusory and irrational.

The Einstein story is also crucial to philosophers. They say that Einstein ignored the evidence and created relativity based on what he thought was right, abruptly overthrowing everything beforehand. Nearly all parts of their story is wrong, as I have detailed on this blog and in my book.

The quantum mechanics revolution is cited less often, because T. Kuhn denied that it was a paradigm shift. It had measurable advantages over the previous theories that were immediately accepted, and therefore did not fit his pattern for scientific revolutions and paradigm shifts.

SciSal, Newtonian mechanics certainly is an approximation to relativity, and this is commonly explained in relativity textbooks and on Wikipedia. Space and time are not two aspects of the same thing in relativity. In spite of your claim that causality does not appear in fundamental physics, space-time in relativity has a causal structure that treats space very differently from time.

It is also not quite right to say that Newtonian mechanics is different because space and time are fixed. Both Newtonian and relativistic mechanics can use coordinate changes in space and time. You say that relativity space-time is continuously dynamic, but it is really the gravitational potential that is continuously dynamic, and a Newtonian potential is also continuously dynamic.

You also claim that classical and quantum mechanics are radically different in how they treat space and time, and hence cannot be applied to the same problems. I disagree. See the correspondence principle for how classical mechanics is a macroscopic approximation to quantum mechanics, contrary to Cartwright.

Alexander is quite right that calling Newtonian physics "wrong" is a rather strange use of the word wrong. Perhaps the historian/philosophers use the word to mean something different from everyone else. Phoffman56 explains this correctly, and he is right that the philosopher quibbles have no credibility at all with physicists.

SciSal argues that Einstein space-time is some sort of exception to the view of steady progress in science. I disagree. The history of relativity was one of steady progress over decades, and was not really so radically different. You can still talk about forces as being the rate of change of momentum, and many other Newtonian concepts carry over.

A theme of this blog is the steady progress of science. See my Latin motto above. I thought this progress was obvious, but most philosophers deny it.

Pigliucci promotes his idea of science in his 2010 book, Nonsense on Stilts: How to Tell Science from Bunk, and in this interview promoting the book. In it, he argues that Newtonian theory of gravity is wrong, because it does not have Einstein's concept of space-time. He acknowledges that string theory might be wrong, but it is not pseudoscience because it is done by smart people and it makes all the same predictions as the Standard Model. He attacks Bjorn Lomborg for speaking about global warming alarmism because his degree is not in climate science.

This is pretty nutty, and Pigliucci himself would be an example of something speaking outside his expertise. The difference between classical mechanics and relativity is not what he thinks. String theory is not able to make any of the Standard Model prediction, and is pseudoscience in the sense of not making any testable predictions. Lomborg is concerned with the economic choices that people make in response to global warming, and he has expertise in that subject (even with the unpopularity of his view that other problems are more important).

Pigliucci represents a common academic philosophy view of what science is about, and he is way off base. His book has many favorable Amazon reviews, such as this ideological one:

A major political party in America has been taken over by the forces of darkness. Purveyors of scientific illiteracy continue to bombard American citizens with their claims about "legitimate rape," the willful ignorance of creationism, denial of global climate change and other aspects of reality. Pigliucci provides common-sense ammuniton for those who will resist this wave of anti-science reality denial.

But you might want to check out the negative reviews, as they have some very specific and damning criticisms.